Devpac and assembling for absolute addresses

h0ffman · 17 March 2011, 20:21

I'm using DevPac to write pretty much all my code. I've managed to crack the whole absolute address / non-system kinda stuff now, however I have one question..

Is it possible to get Devpac to assemble to an absolute address without adding all the hunks and shit at the start of the file.

The end result I need is just a data file with everything in it, the hunk at the start is REALLY annoying.

pmc · 17 March 2011, 20:24

To be loaded with a trackloader or something...?

You could use asmone to assemble and then wb (write binary) to the floppy. That way you just get the data of your file and no hunks. For your code to work like this when you jump into it though you'll probably need it all to be pc relative.

hitchhikr · 17 March 2011, 20:37

It don't remember it being possible with devpac (absolute addressing wasn't considered a good practice back then) better use vasm, it can generate absolute/relocated binary output and is generally very handy (& can even generate chip located hunks to use with gcc).

Wepl · 17 March 2011, 22:29

don't know how it works in devpac, but you could use tools like reloc to convert them afterwards

Galahad/FLT · 17 March 2011, 22:33

Quote:

Originally Posted by h0ffman

I'm using DevPac to write pretty much all my code. I've managed to crack the whole absolute address / non-system kinda stuff now, however I have one question..

Is it possible to get Devpac to assemble to an absolute address without adding all the hunks and shit at the start of the file.

The end result I need is just a data file with everything in it, the hunk at the start is REALLY annoying.

The easiest and quickest way I did it 'back in the day' is to compress the file with an absolute capable cruncher (Crunchmania etc), set it to the start address you want, let it pack the file, then once its packed, depack it again, and all reloc headers and stuff is removed and your file is now absolute addressed to what you specified in the cruncher.

I'm sure theres a specific tool to do the job (I had my own routines for PM3 Deluxe!), but its what I did in lieu of the tools.

Leffmann · 20 March 2011, 17:02

If your code can't be assembled without modification in ASM-One or if you insist on using DevPac, then one alternative is to insert some code in the beginning of your program which writes the rest of the code to disk for you.

EDIT: this works and can just be copy-pasted right in

Code:

             org $40000-76-14

savebinary   move.l  4.w, a6
             lea     _doslib(pc), a1
             jsr     -408(a6)
             move.l  d0, a6

             lea     _file(pc), a0
             move.l  a0, d1
             move.l  #1006, d2
             jsr     -30(a6)
             move.l  d0, d4
             beq.b   _exit

             move.l  d0, d1
             lea     progstart(pc), a0
             move.l  a0, d2
             move.l  _length(pc), d3
             jsr     -48(a6)

             move.l  d4, d1
             jsr     -36(a6)

_exit        moveq   #0, d0
             rts

_length      dc.l    proglength
_doslib      dc.b    "dos.library", 0
_file        dc.b    "ram:code.bin", 0, 0


progstart

             code goes in here

proglength   = *-progstart

h0ffman · 21 March 2011, 10:31

Hi Guys

Thanks for the tips. I found a way to manage this now. I specify the ORG address in the code and put a string at the end of the code and data. Assemble, Debug, search for string then I can save the binary out of memory. Works wells, just a bit fiddly.

phx · 21 March 2011, 11:00

If you don't want to use an assembler supporting raw-binary output there is still another option for you: use a linker, like vlink.

1. Create an object file with your assembler.
2. Convert it into a raw binary file with vlink:

Code:

$ vlink -brawbin1 -o filename filename.o

Lonewolf10 · 21 March 2011, 18:41

Quote:

Originally Posted by Leffmann

Code:

progstart

             code goes in here

proglength   = *-progstart

Does the asterisk do something special, or should it be replaced with a progend marker?

Regards,
Lonewolf10

StingRay · 21 March 2011, 18:50

Quote:

Originally Posted by Lonewolf10

Does the asterisk do something special, or should it be replaced with a progend marker?

* = current PC so it does not need to be replaced with anything, it's just used to calculate the length without any additional label.

Lonewolf10 · 21 March 2011, 19:12

Quote:

Originally Posted by StingRay

* = current PC so it does not need to be replaced with anything, it's just used to calculate the length without any additional label.

Thanks for that StingRay. That's another thing I'll add to my ASM notes

Regards,
Lonewolf10

21 March 2011, 11:00	#8
phx Natteravn Join Date: Nov 2009 Location: Herford / Germany Posts: 2,500	If you don't want to use an assembler supporting raw-binary output there is still another option for you: use a linker, like vlink. 1. Create an object file with your assembler. 2. Convert it into a raw binary file with vlink: Code: $ vlink -brawbin1 -o filename filename.o

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17 March 2011, 20:21	#1
h0ffman Registered User Join Date: Aug 2008 Location: Salisbury Posts: 744	Devpac and assembling for absolute addresses I'm using DevPac to write pretty much all my code. I've managed to crack the whole absolute address / non-system kinda stuff now, however I have one question.. Is it possible to get Devpac to assemble to an absolute address without adding all the hunks and shit at the start of the file. The end result I need is just a data file with everything in it, the hunk at the start is REALLY annoying.

17 March 2011, 20:24	#2
pmc gone Join Date: Apr 2007 Location: completely gone Posts: 1,596	To be loaded with a trackloader or something...? You could use asmone to assemble and then wb (write binary) to the floppy. That way you just get the data of your file and no hunks. For your code to work like this when you jump into it though you'll probably need it all to be pc relative.

17 March 2011, 20:37	#3
hitchhikr Registered User Join Date: Jun 2008 Location: somewhere else Posts: 515	It don't remember it being possible with devpac (absolute addressing wasn't considered a good practice back then) better use vasm, it can generate absolute/relocated binary output and is generally very handy (& can even generate chip located hunks to use with gcc).

17 March 2011, 22:29	#4
Wepl Moderator Join Date: Nov 2001 Location: Germany Posts: 866	don't know how it works in devpac, but you could use tools like reloc to convert them afterwards

21 March 2011, 10:31	#7
h0ffman Registered User Join Date: Aug 2008 Location: Salisbury Posts: 744	Hi Guys Thanks for the tips. I found a way to manage this now. I specify the ORG address in the code and put a string at the end of the code and data. Assemble, Debug, search for string then I can save the binary out of memory. Works wells, just a bit fiddly.

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